Abstract

Distortion-product otoacoustic emission (DPOAE) suppression data as a function of suppressor level (L3) for f2 frequencies from 0.5 to 8 kHz and L2 levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L3 functions, and the L3 levels resulting in 3 dB decrements were derived by transformed linear regression. These L3 levels were plotted as a function of f3 to construct STCs. When f3 is represented on an octave scale, STCs were similar in shape across f2 frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (QERB). Both gain and tuning decreased as L2 increased, regardless of f2, but the trend with f2 was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4–16 dB (mean ≈ 5 dB) for every unit increase in QERB, although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent.

Received 01 June 2010Accepted 29 November 2010Published online 11 February 2011

Acknowledgments:

This work was supported by the National Institutes of Health (NIH) (Grant Nos. R01 DC2251 and P30 DC4662). We thank Sandy Estee for her help in subject recruitment. We thank Rachel Scheperle, Natalie Lenzen, Elizabeth Searing, Michelle Parks, Megan Thorson, and Rachel Tomasek for their help with data collection. We also thank Megan Thorson for her help with the preparation of figures. Finally, we thank Brenda Lonsbury-Martin, Caroline Abdala, and one anonymous reviewer for helpful suggestions on an earlier version of this manuscript.

Article outline:I. INTRODUCTIONII. METHODSIII. RESULTS AND DISCUSSIONA. Comparisons of DPOAE STCs across all f2, L2 combinationsB. Comparison of STCs on a log-frequency axisC. L3 for 3 dB of suppression as a function of L2 for low-frequency and “on-frequency” suppressorsD. Estimates of tuning and BFE. The gain–bandwidth trade-offF. Important limitation in the present dataIV. CONCLUSIONS